Papers by Keyword: Free Vibration Analysis

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Authors: Wei Ning, Feng Sheng Peng, Nan Wang, Dong Sheng Zhang
Abstract: The free vibrations of the stiffened hollow conical shells with different variable thickness distribution modes are investigated in detail in the context of Donnel-Mushtari conical shell theory. Two sets of boundary conditions have been considered. The algebraic energy equations of the conical shell and the stiffeners are established separately. The Rayleigh-Ritz method is used to equate maximum strain energy to maximum kinetic energy which leads to a standard linear eigenvalue problem. Numerical results are presented graphically for different geometric parameters. The parametric study reveals the characteristic behavior which is useful in selecting the shell thickness distribution modes and the stiffener type. The comparison between the present results and those of finite element method shows that the present results agree well with those of finite element method.
121
Authors: Zhen Yan Xiao, Yun Gong, Yao Qing Gong
Abstract: A method based on Ordinary Differential Equations (ODE) solver for free vibration analysis of tubular structures of tall buildings is developed, considering the deformation of the foundation soil as well as the interactions between the foundation and soil, by means of a three dimensional model with continuously distributed mass and stiffness. The nodal lines employed to discretize the computational model of the structures are one-variable functions defined on the nodal lines selected by the analyst to describe the dynamic behavior of the model. The unknown functions determined numerically herein are actual vibration modes that can be also recognized as the deformation functions of a set of conceptual structural components. By a Hamiltonian principle, the governing equations of the free vibration analysis can be obtained, which are a set of ordinary differential equations (ODE) of the vibration modes with their corresponding boundary conditions. The desired frequencies and corresponding vibration modes can be obtained by numerically solving the ODEs with boundary conditions. The method is applied to the tubular structures of tall buildings. The results from the illustration example show that the method is rational and powerful for the free vibration analysis of tall buildings.
194
Authors: Jun Xia, Z. Shen, Kun Liu
Abstract: The tapered cross-section beams made of steel-concrete composite material are widely used in engineering constructions and their dynamic behavior is strongly influenced by the type of shear connection jointing the two different materials. The 1D high order finite element model for tapered cross-section steel-concrete composite material beam with interlayer slip was established in this paper. The Numerical results for vibration nature frequencies of the composite beams with two typical boundary conditions were compared with ANSYS using 2D plane stress element. The 1D element is more efficient and economical for the common tapered cross-section steel-concrete composite material beams in engineering.
380
Authors: S.H. Hosseini Hashemi, S. Fazeli
Abstract: In this paper the free vibration analysis of a fiber reinforced mindlin plate is presented.energy method based on the ritz method is used to obtain natural frequencies of the plate. Displacement fields of the plate are postulated by trigonometric series function. depending on the arrangement and orientation of the fibers, mindlin plate is assumed to be orthotropic or monoclinic.this analysis is useful to study the mechanical behavior of an angle ply lamina and effect of fiber orientation on the frequency response of the plate.the analysis can be extended for the laminates where the analytical solutions are not available. Finally the results are compared with those reported in the literature.
350
Authors: Zhi Hao Wang
Abstract: The classical outrigger in frame-core tube structure cantilevering from the core tube or shear wall connected to the perimeter columns directly, which can effectively improve the lateral stiffness of the structure. A new energy-dissipation system for such structural system is studied, where the outrigger and perimeter columns are separate and vertical viscous dampers are equipped between the outrigger and perimeter columns to make full use of the relative big displacement of two components. The effectiveness of proposed system is evaluated by means of the modal damping ratio based on the proposed simplified model. The mathematic models of the structural system are obtained with both the assumed mode shape method and finite element method according to the simplified calculation diagram. Based on the modal damping ratio, the optimal damping coefficients of linear viscous dampers are determined, and effectiveness of proposed system is confirmed.
648
Authors: Wei Ning, Dong Sheng Zhang, Ji Ling Jia
Abstract: The free vibrations of the stiffened hollow conical shells with different variable thickness distribution modes are investigated in detail in the context of Donnel-Mushtari conical shell theory. Two sets of boundary conditions have been considered. The algebraic energy equations of the conical shell and the stiffeners are established separately. The Rayleigh-Ritz method is used to equate maximum strain energy to maximum kinetic energy which leads to a standard linear eigenvalue problem. Numerical results are presented graphically for different geometric parameters. The parametric study reveals the characteristic behavior which is usefulis inuseful in selecting the shell thickness distribution modes and the stiffener type.
7
Authors: Ali Fallah, Mohammad Hossein Kargarnovin, Mohammad Mohammadi Aghdam
Abstract: In this paper, free vibration analysis of thin symmetrically laminated skew plates with fully clamped edges is investigated. The governing differential equation for skew plate which is a fourth order partial differential equation (PDE) is obtained by transforming the differential equation in Cartesian coordinates into skew coordinates. Based on the multi-term extended Kantorovich method (MTEKM) an efficient and accurate approximate closed-form solution is presented for the governing PDE. Application of the MTEKM reduces the governing PDE to a dual set of ordinary differential equations. These sets of equations are then solved with infinite power series solution, in an iterative manner until convergence was achieved. Results of this study show the fast rate of convergence of the MTEKM. Usually two or three iterations are enough to obtain reasonably accurate results. The frequency parameters of laminated composite plates are obtained for different skew angles and lay-up configuration for different composites laminates skew plates. Comparisons have been made with the available results in the literature which show the accuracy and efficiency of the method.
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